The present invention relates to sensor elements for mounting on the fingertips of a robot hand or an artificial hand or the like in order to provide fine power adjustments that are required when grasp control operations or the like are performed, and to object movement control devices for controlling movement of objects and object judgment devices for discriminating objects, both of the aforementioned devices incorporating the sensor elements mounted on the fingertips of a robot hand or the like.
In recent years, research and development of multi-finger robot hands resembling human hands, and artificial hands has been undertaken with one of two objectives: the first, to provide robot hands or artificial hands capable of being used to perform operations on behalf of humans in places in places where it is difficult or potentially hazardous for humans to undertake the operations directly, such as operations performed in outer space and deep sea exploration, and operations in which an explosion may occur; the second, to provide prosthetic hands for people with physical disabilities in order to compensate for impeded functionality of their hands.
Further, in order to realize a level of operational dexterity more closely approaching that of the human hand, sensor elements for mounting on the fingertips of a robot hand, an artificial hand or the like, and which are capable of realizing the level of fine power adjustment required for grasp control have been developed and placed on the market.
Sensor devices such as those described above are known in which the control of grasping force is facilitated by detecting the amount of pressure applied to the sensor element. For example, Non-patent Reference No. 1 describes a capacitance pressure sensor device configured to facilitate control of the grasping force applied to the sensor element by measuring the capacitance between a pair of electrodes provided on a capacitance pressure sensor element. Non-patent Reference No. 2 describes an example of a pressure sensitive conductive elastomer sensor device configured to facilitate control of grasping force by measuring the amount of pressure applied to a pressure sensitive elastomer sensor element by detecting changes in the resistance between a pair of electrodes between which a pressure sensitive electrically conductive rubber has been inserted.
Further, sensor devices are also known in which the control of grasping force is facilitated by detecting contact between the sensor device and an object of grasping. For example, Non-patent Reference No. 3 describes a micro-pressure sensor device, which is provided with a vibrating tactile sensor disposed on the sensor device so as to be able to come into contact with an object of grasping, configured to facilitate control of grasping force through detecting contact with an object of grasping by measuring the viscoelastic property shown by changes in the magnitude and frequency of the vibrations when the vibrating tactile sensor has come into contact with the object of grasping.
Still further, Non-patent Reference No. 4 describes an example of a resonance tensor cell tactile sensor device that utilizes the ultra sound resonance phenomenon to detect changes in the dimensions of a spherical cavity provided within an elastic body so as to detect pressure applied to the elastic body so as to facilitate control of the grasping force. Further still, Non-patent Reference No. 5 describes an example of a distributed contact sensor device configured to facilitate control of the grasping force by use of a contacting surface slippage sensor element provided with a distributed strain gauge capable of detecting local slippage occurring between an object of grasping and the sensor element.    Non-patent Reference 1: “T-2000 Adaptable array tactile sensor”, SysCom, Inc., accessed on Nov. 27, 2002 at http://www.syscom-inc.co.jp/pps_array.pdf    Non-patent Reference 2: “Inastomer”, Inaba Rubber, Inc., accessed on Nov. 27, 2002 at http://www.inaba-rubber.co.jp/katarogu/inast/inast.html    Non-patent Reference 3: “Micro tactile sensor catheter research”, Olympus Optical, Inc., accessed on Nov. 27, 2002 at http://www.oympus.co.jp/Special/OTF80/mskt.html    Non-patent Reference 4: “TORAO research themes”, Shinoda Labs, Department of Computer Science, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, accessed on Nov. 27, 2002 at http://www.alab.t-u-tokyo.ac.jp/-shinolab/members/torao/kenkyu/kenkyul.html    Non-patent Reference 5: “Distributed tactile sensor for control of grasping force”, Maeno Laboratory, Department of Mechanical Engineering, Keio University, accessed on Nov. 27, 2002 at http://www.maeno.mech.keio.ac.jp/sensor2/sensor2.htm